Electrical conductor



NOV. 17, 1936. l WEAVER 2,060,913

ELECTRICAL CONDUCTOR Filed July 7, 1934 F/G. 4. A F16.

/NVENOR L. 1 WEAVER ATTORNEY Patented Nov. 17, 1936 PATENT OFFICEELECTRICAL CONDUCTOR Leo L. Weaver, Cranford, N. J., assignor to WesternElectric Company, Incorporated, New York, N. Y., a corporation ofNewYork Application July 7, 1934, Serial N0. 734,082

1 Claim.

This invention relates to electrical conductors and more particularlyto` multiple conductor cords or cables.

The cords used to connectr a telephone receiver to the base of theinstrument and the base to the bell box must be of sutlicient length andexibility, especially in the case of a desk telephone to permit ofconvenient use over a relatively wide area. At the same time in somecases it is preferable that these cords should not be in the way whenthe instrument is not in use. Similar considerations apply to the powercords used to supply current to lamps, fiat irons, toasters and otherelectrical devices. Many devices in the Iorm of variously coiled andshaped spring wires to be applied to or over such cords have beensuggested.

An object of the invention is to provide a self coiling cord orconductor which is so constructed as to form itself into a neat andcompact coil when not under tension without the application thereto ofany extraneousl means or device not normally included in the structureof such conductors or cords, and which shall nevertheless yield easilyto tension tending to elongate the coil. In one embodiment of theinvention, one or lmore of the three metallic conductor strands of thecustomary telephone cord is made of some material such as a phosphorbronze alloy, which combines both satisfactorily high `electricalconductivity and mechanical elasticity, and is formed as a flattenedtape wound in a resilient helix or Fig. 1 is a plan view of a length ofthree con-A ductor cord constructed and formed in accord- 50 ance withthe invention;

Fig. 2 is a view thereof in side elevation; Fig. 3 is an enlargedsectional View on the line '3f-3' of Fig. 2; Fig. 4 is a view similar toFig. 1 of a modified 55 form; f

rection of its coil axis and tends to resume its Fig. 5 is a viewsimilar to Fig. 2 of another modified form; I

Fig. 6 is lan enlarged sectional view on the line 6-6 of Fig. 5, and

Fig. "I is an enlarged sectional view of a third modication.

The embodiment of theinvention disclosed in Figs. 1, 2, and 3 comprisesthree conductors 20, 2|, and 22. These are flat tapes of rectangularcross section coiled in a resilient cylindrical helix whose curvature issubstantially in the plane of the tapes. The tapes are made preferablyof a phosphor bronze alloy or other material having both satisfactoryelectrical conductivity and4 mechanical elasticity.

The middle tape 2| is individually covered with a braided protective andinsulating sheath 23 of textile libres, and the three tapes together arecovered with a similar outer sheath 24.

Instead of coiling the cord in a helix as shown in Fig. 2, it may insome cases be preferable to coil it as a fiat resilient spiral as shownin Fig. 4. In either case the coiled form is held and sustained by thecoiled ilat conductors and not by any added member.

Figs. 5 and 6 discloses a modiiied form of the invention in which thereis only one conductor in the cord and in which the cross sectionl of theconductor is elliptical or oval and is formed into al helix with theprincipal curvature in the plane of the greatest cross section-dimensionof the conductor.

A cord or cable made and formed in accordance Awith the invention mayhave any number oi conductors associated together provided that one ofthe conductors be elastic and have a cross section of greater dimensionin one of two mutually perpendicular directions than in the other, sothat if the cord beformed-as a coil with its curvature in the plane ofthe greater cross section dimension of the attened conductor, it willflex easily across that plane but will resist flexure in the plane.

'Ihus Fig. 7 is a cross section of a cord embodying the invention inwhich a single flat tape conductor 2| is combined with two ordinaryround or stranded conductors |20 and |22 and the whole may be coiled ina resilient spiral or helix with the curvature in the plane of the tape2|.

One advantage of the construction disclosed in Figs. l, 2, and 3 is thesaving in covering material. The fiat tape-like conductors enclosed inthe sheath 24 are held thereby against relative lateral displacement,and in particular conductors 20 and 22 cannot slide around conductor 2land make contact with each other.

Hence for mutual insulative separation of the three conductors it isnecessary only to cover the middle conductor 2| individually, whereas iiall three were circular in cross section, no one could be relied upon toseparate the other two. The same is true of the construction shown inFig. 7.

In the disclosure above it is suggested that the conductive strands 20,2|, and 22 be made of phosphor bronze. This is a preferred c0nstructionsince such alloys are at the same time highly electrically conductiveand also highly mechani cally elastic. The invention is not, however,coniined to this material as in some instances other materials such asspring brass, some spring steels, certain nickel alloys such as monel,nichrome and the like, and for some uses hard drawn alloys of aluminumcould be used.

For simplicity and clarity of statement the phrase substantially ilat"as applied to the cross section of a conductor will hereinafter be usedto mean a cross section greater in one direction than in any other. andthus will include oval, elliptical, rectangular but not square, rhombicor rhomboidal cross sections and the like. Also the phrases coiled inthe plane of the conductor" or coiled in the plane of the strand" willbe similarly used to mean coiled so that the curvature of coiling. issubstantially `in or wallel to a plane passing through the conductor orstrand in the direction of the greatest dimension of the cross sectionof the conductor or strand.

'I'he embodiments of the invention herein disclosed' are illustrativemerely and may be modiiled and departed from in many ways withoutdeparting from the spirit and scope o! the invention as pointed out inand limited solely by the appended claim.

What isclaimed is:

An electrical conductor cord comprising three strands each a unitarycombined conductor and coiling spring and each of material both`electrically conductive and mechanically elastic and each formed with asubstantially flat cross section and the three cross sections beingmutually parallel, a sheath of insulating material on the middle strand,and a sheath of insulating material over the whole, the whole conductorcord being coiled in the plane oi' the ilat strands, whereby the coiledconductor is easily elastically deformable under stress along the axisof the coils thereof and tends to return to its coiled :form whenreleased from stress.

LEO L. WEAVER.

